Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解

摘要：，，本文介绍了Android和Linux系统中GPIO（General Purpose Input/Output）的控制方法。文章首先概述了GPIO的基本概念及其在操作系统中的作用，然后详细描述了如何在Android和Linux平台上进行GPIO的配置和控制，包括相关命令、编程接口以及操作步骤。文章旨在帮助开发者理解并实现在这些系统中对GPIO的有效控制，以促进硬件交互和系统集成。

1 GPIO整体架构

2 user space 层 gpio使用方法

2.1 sysfs控制方法

2.1.1 kernel版本区别

2.1.2 /sys/class/gpio

2.1.3 /sys/bug/gpio/devices

2.2 chardev控制方法

2.2.1 chardev 示例代码

2.2.2 示例代码主要步骤描述

2.2.3 include/linux/gpio.h 全部代码

2.3 gpiolib_tools

2.3.1 gpiodetect

2.3.2 gpioinfo

2.3.3 gpio-event-mon

2.4 gpiolib-debugfs

2.4.1 /sys/kernel/debug/gpio

2.4.2/sys/kernel/debug/gpio/pinctrl

3 kernel空间使用gpio

3.1 pinctrl子系统概念

3.1.1 pinctrl 子系统 DTS设定

3.1.2 pinctrl 子系统 driver设定

3.2 gpio子系统

3.2.1 gpio子系统 DTS设定

3.2.2 gpio子系统 driver设定

4 gpio IRQ相关简述

4.1 linux中断描述及常用API

4.2 GPIO中断API

4.3 GPIO中断使用代码示例：

4.4 gpio中断效果确认

1 GPIO整体架构

从Linux kernel 2.6.24开始，GPIO控制核心就通过gpiolib来进行实现了。

gpiolib初始提交信息：

gpiolib: add gpio provider infrastructure - kernel/git/torvalds/linux.git - Linux kernel source tree

gpiolib初始提交代码：

gpiolib.c « gpio « drivers - kernel/git/torvalds/linux.git - Linux kernel source tree

关于gpio的使用block图如下：

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第1张

对于hardware层：

GPIO controller是硬件物理结构

对于kernel space层：

芯片厂商的bsp工程师负责gpio chip driver
开源社区（linux kernel）的大佬负责gpiolib的核心功能实现

BSP开发担当负责编写gpio consumer driver，可以从kernel driver中控制gpio

对于user space层：

APP开发担当可以从user space 使用sysfs和chardev的形式控制gpio

因此正常情况下，BSP及APP开发不需要深入GPIO chip driver和gpiolib，仅了解其使用方式即可

2 user space 层 gpio使用方法

2.1 sysfs控制方法

查看kernel版本中关于gpiofs的官方描述，可以通过kernel官网

网址：kernel.org/doc/Documentation/gpio/sysfs.txt

2.1.1 kernel版本区别

上述网站中最新的描述中可以看到gpio sysfs已经弃用了

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第2张

查看相关资料时发现，这个改动是从2015年逐渐从linux kernel4.6开始引入的，至到4.8版本（2020年）正式废弃。这部分的提交代码如下：

网址：gpio: add a userspace chardev ABI for GPIOs - kernel/git/torvalds/linux.git - Linux kernel source tree

所以在kernel4.8以前可以直接使用gpio sysfs的方法来控制gpio。

如果在4.8以后，想要再使用这个接口，可以通过改变menuconfig的方式打开CONFIG_GPIO_SYSFS，然后就可以继续使用gpio sysfs来控制gpio了。

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第3张

2.1.2 /sys/class/gpio

该目录下的gpio可以直接通过命令进行操作。

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第4张

该目录下有个export文件，向export文件写入要操作的GPIO号，使得该GPIO的操作接口从内核空间暴露到用户空间，GPIO的操作接口包括direction和value等，direction控制GPIO输入或者输出模式，而value可控制GPIO的状态或者读取状态。

/sys/class/gpio/目录下各个文件说明：

/sys/class/gpio/export文件用于通知系统需要导出控制的GPIO引脚编号；

/sys/class/gpio/unexport 用于通知系统取消导出；

/sys/class/gpio/gpioX/direction文件，可以通过echo写入in（设置输入方向）或out（设置输出方向）；通过cat读出输入方向

/sys/class/gpio/gpioX/value文件是可以读写GPIO状态；echo 写入，cat读出

/sys/class/gpio/gpiochipX目录保存系统中GPIO寄存器的信息，包括每个寄存器控制引脚的起始编号，寄存器名称，引脚总数；其中X表示具体的引脚编号。

对于组别和编号的判断，在此目录下使用命令： for file in ./gpiochip*/label;do echo -n "$file ------->";cat "$file";done; 可以确认端子组别信息

效果如下：

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第5张

上述内容gpc对应的gpio起始编号为61，如果此时想要操作gpc_0，则对应编号则为61+0=61

使用echo 61 > export则可以导出gpc_0的端子文件目录

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第6张

进入gpio61 目录后可以通过 cat 获取当前gpio的电平状态和输入输出状态，也可以通过echo命令改变gpio输出的电平状态

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第7张

通过echo和cat命令确认gpio输入输出模式

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第8张

上述的控制台命令在app的代码上可以使用system函数取代例如：

void GPIO_LOW_SET(void)
{
    system("echo 247 > /sys/class/gpio/export");
    system("echo out > /sys/class/gpio/gpio247/direction");
    system("echo 0 > /sys/class/gpio/gpio247/value");
    system("echo 248 > /sys/class/gpio/export");
    system("echo out > /sys/class/gpio/gpio248/direction");
    system("echo 0 > /sys/class/gpio/gpio248/value");   
    
    system("echo 249 > /sys/class/gpio/export");
    system("echo out > /sys/class/gpio/gpio249/direction");
    system("echo 0 > /sys/class/gpio/gpio249/value");   
    
}

2.1.3 /sys/bug/gpio/devices

确认gpio组别不仅可以通过上述 /gpio/class/gpio/gpiochip*/label 取得。

还可以通过 /sys/bus/gpio/devices/gpiochip* /of_node/name 取得

在/sys/bus/gpio/devices目录下使用命令：

for file in ./gpiochip* ;do echo -n "$file ------->";cat "$file/of_node/name";echo ;done;

结果效果：

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第9张

其实/sys/bus/gpio/devices和/sys/class/gpio的区别到底在哪呢？在此不详细说明，通过下面的内容也许能为你提供一些灵感。（下图可能也表明了/sys/bus和/sys/class的一些奥妙！）

/sys/bus/gpio/devices

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第10张

/sys/class/gpio

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第11张

2.2 chardev控制方法

通过【1gpio整体架构】的block图可以看到主要使用的节点是/dev/gpiochip*，这是一个设备节点。对于app的开发，应当使用open，ioctl，write，read等文件接口对它进行操作。

可操作的设备在/dev下都命名为gpiochip* 如下图：

Android&Linux GPIO控制方法，Android与Linux的GPIO控制方法详解第12张

相关libgpiod网页：libgpiod/libgpiod.git - C library and tools for interacting with the linux GPIO character device (kernel.org)

2.2.1 chardev 示例代码

下面是一段用于拉高gpiochip4_4的示例代码

#include 
#define HIGH                        (1)
#define LOW                         (0)
#define RES_NG                      (1)
#define RES_OK                      (0)
#define INIT_STATUS_LINES 4
#define  INIT_STATUS_GPIOCHIPS "/dev/gpiochip4"
/********************************************************************************/
/* Function Name        : nswWrite_PowerGPIO_Value                              */
/* Date                 : 2024/01/11                                            */
/* Author               : HeartJoKer                                            */
/* Description          : Set Power Gpio:INIT_STATE Value                       */
/* Argument Code        : none   */
/* Return Code          : Type_sWord    aswRet 0 is OK,1 is NG                  */
/* Tips                 : GPIO 相关宏及结构体定义参考/include/linux/gpio.h       */
/*------------------------------------------------------------------------------*/
/* Revision History              */
/* No.        Date                  Revised by          Function Name           */
/* 0001    2024/01/11               HeartJoKer            New                   */
/********************************************************************************/
Type_sWord nswWrite_PowerGPIO_Value()
{
    Type_sWord aswRet = RES_NG;
    Type_sWord aswLineFd = 0;
    Type_sWord aswChipFd = 0;
    struct gpiohandle_data astData;
    struct gpiohandle_request astreq;
    memset(&astData,0,sizeof(astData));
    memset(&astreq,0,sizeof(astreq));
    ALOGI("Start to Set GPIO:INIT_STATUS Vaule");
    aswChipFd = open(INIT_STATUS_GPIOCHIPS, 0);
    if(aswChipFd  
2.2.2 示例代码主要步骤描述 
其中有四步关键内容 
①open(INIT_STATUS_GPIOCHIPS, 0); 
②ioctl(aswChipFd, GPIO_GET_LINEHANDLE_IOCTL, &astreq) 
③ioctl(astreq.fd, GPIOHANDLE_SET_LINE_VALUES_IOCTL, &astData) 
④ close(aswChipFd) 
再提及这四个具体步骤之前，要明确两个概念 
概念一：gpiochip_group:参照上文提到的gpiochip，对应不同gpio组，例如： 
 
概念二：gpiochip_group_line：对应每一个gpiochip_group每一组下的每一个gpio  
 
       结合上述两个概念，gpioe-4，即/dev/gpiochip4--->line4 
      明确上述概念后，上述代码的四步逻辑就能比较清晰的理解 
        ①选择gpiochip，通过open函数获取对应dev的Fd句柄 
        ②通过ioctl获取对应Line句柄 
        ③通过ioctl上述选择的Line进行操作 
        ④关闭dev设备 
 
对于②③可用的ioctrl宏参照如下：（include/linux/gpio.h） 
/*
 * v1 and v2 ioctl()s
 */
#define GPIO_GET_CHIPINFO_IOCTL _IOR(0xB4, 0x01, struct gpiochip_info)
#define GPIO_GET_LINEINFO_UNWATCH_IOCTL _IOWR(0xB4, 0x0C, __u32)
/*
 * v2 ioctl()s
 */
#define GPIO_V2_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x05, struct gpio_v2_line_info)
#define GPIO_V2_GET_LINEINFO_WATCH_IOCTL _IOWR(0xB4, 0x06, struct gpio_v2_line_info)
#define GPIO_V2_GET_LINE_IOCTL _IOWR(0xB4, 0x07, struct gpio_v2_line_request)
#define GPIO_V2_LINE_SET_CONFIG_IOCTL _IOWR(0xB4, 0x0D, struct gpio_v2_line_config)
#define GPIO_V2_LINE_GET_VALUES_IOCTL _IOWR(0xB4, 0x0E, struct gpio_v2_line_values)
#define GPIO_V2_LINE_SET_VALUES_IOCTL _IOWR(0xB4, 0x0F, struct gpio_v2_line_values)
/*
 * v1 ioctl()s
 *
 * These ioctl()s are deprecated.  Use the v2 equivalent instead.
 */
#define GPIO_GET_LINEINFO_IOCTL _IOWR(0xB4, 0x02, struct gpioline_info)
#define GPIO_GET_LINEHANDLE_IOCTL _IOWR(0xB4, 0x03, struct gpiohandle_request)
#define GPIO_GET_LINEEVENT_IOCTL _IOWR(0xB4, 0x04, struct gpioevent_request)
#define GPIOHANDLE_GET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x08, struct gpiohandle_data)
#define GPIOHANDLE_SET_LINE_VALUES_IOCTL _IOWR(0xB4, 0x09, struct gpiohandle_data)
#define GPIOHANDLE_SET_CONFIG_IOCTL _IOWR(0xB4, 0x0A, struct gpiohandle_config)
#define GPIO_GET_LINEINFO_WATCH_IOCTL _IOWR(0xB4, 0x0B, struct gpioline_info)
 使用这些宏时需要关注其相关结构体，例如上文中使用
②GPIO_GET_LINEHANDLE_IOCTL----> gpiohandle_request
对应结构体
 /**
 * struct gpiohandle_request - Information about a GPIO handle request
 * @lineoffsets: an array of desired lines, specified by offset index for the
 * associated GPIO device
 * @flags: desired flags for the desired GPIO lines, such as
 * %GPIOHANDLE_REQUEST_OUTPUT, %GPIOHANDLE_REQUEST_ACTIVE_LOW etc, added
 * together. Note that even if multiple lines are requested, the same flags
 * must be applicable to all of them, if you want lines with individual
 * flags set, request them one by one. It is possible to select
 * a batch of input or output lines, but they must all have the same
 * characteristics, i.e. all inputs or all outputs, all active low etc
 * @default_values: if the %GPIOHANDLE_REQUEST_OUTPUT is set for a requested
 * line, this specifies the default output value, should be 0 (low) or
 * 1 (high), anything else than 0 or 1 will be interpreted as 1 (high)
 * @consumer_label: a desired consumer label for the selected GPIO line(s)
 * such as "my-bitbanged-relay"
 * @lines: number of lines requested in this request, i.e. the number of
 * valid fields in the above arrays, set to 1 to request a single line
 * @fd: if successful this field will contain a valid anonymous file handle
 * after a %GPIO_GET_LINEHANDLE_IOCTL operation, zero or negative value
 * means error
 *
 * Note: This struct is part of ABI v1 and is deprecated.
 * Use &struct gpio_v2_line_request instead.
 */
struct gpiohandle_request {
	__u32 lineoffsets[GPIOHANDLES_MAX];
	__u32 flags;
	__u8 default_values[GPIOHANDLES_MAX];
	char consumer_label[GPIO_MAX_NAME_SIZE];
	__u32 lines;
	int fd;
};
 ③GPIOHANDLE_SET_LINE_VALUES_IOCTL -> gpiohandle_data
    对应结构体描述
 /**
 * struct gpiohandle_data - Information of values on a GPIO handle
 * @values: when getting the state of lines this contains the current
 * state of a line, when setting the state of lines these should contain
 * the desired target state
 *
 * Note: This struct is part of ABI v1 and is deprecated.
 * Use &struct gpio_v2_line_values instead.
 */
struct gpiohandle_data {
	__u8 values[GPIOHANDLES_MAX];
};
 2.2.3 include/linux/gpio.h 全部代码
gpio.h整体内容如下 ，可以详细了解：
 /* SPDX-License-Identifier: GPL-2.0-only WITH Linux-syscall-note */
/*
 *  - userspace ABI for the GPIO character devices
 *
 * Copyright (C) 2016 Linus Walleij
 *
 * This program is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 as published by
 * the Free Software Foundation.
 */
#ifndef _UAPI_GPIO_H_
#define _UAPI_GPIO_H_
#include 
#include 
#include 
/*
 * The maximum size of name and label arrays.
 *
 * Must be a multiple of 8 to ensure 32/64-bit alignment of structs.
 */
#define GPIO_MAX_NAME_SIZE 32
/**
 * struct gpiochip_info - Information about a certain GPIO chip
 * @name: the Linux kernel name of this GPIO chip
 * @label: a functional name for this GPIO chip, such as a product
 * number, may be empty (i.e. label[0] == '')
 * @lines: number of GPIO lines on this chip
 */
struct gpiochip_info {
	char name[GPIO_MAX_NAME_SIZE];
	char label[GPIO_MAX_NAME_SIZE];
	__u32 lines;
};
/*
 * Maximum number of requested lines.
 *
 * Must be no greater than 64, as bitmaps are restricted here to 64-bits
 * for simplicity, and a multiple of 2 to ensure 32/64-bit alignment of
 * structs.
 */
#define GPIO_V2_LINES_MAX 64
/*
 * The maximum number of configuration attributes associated with a line
 * request.
 */
#define GPIO_V2_LINE_NUM_ATTRS_MAX 10
/**
 * enum gpio_v2_line_flag - &struct gpio_v2_line_attribute.flags values
 * @GPIO_V2_LINE_FLAG_USED: line is not available for request
 * @GPIO_V2_LINE_FLAG_ACTIVE_LOW: line active state is physical low
 * @GPIO_V2_LINE_FLAG_INPUT: line is an input
 * @GPIO_V2_LINE_FLAG_OUTPUT: line is an output
 * @GPIO_V2_LINE_FLAG_EDGE_RISING: line detects rising (inactive to active)
 * edges
 * @GPIO_V2_LINE_FLAG_EDGE_FALLING: line detects falling (active to
 * inactive) edges
 * @GPIO_V2_LINE_FLAG_OPEN_DRAIN: line is an open drain output
 * @GPIO_V2_LINE_FLAG_OPEN_SOURCE: line is an open source output
 * @GPIO_V2_LINE_FLAG_BIAS_PULL_UP: line has pull-up bias enabled
 * @GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN: line has pull-down bias enabled
 * @GPIO_V2_LINE_FLAG_BIAS_DISABLED: line has bias disabled
 * @GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME: line events contain REALTIME timestamps
 */
enum gpio_v2_line_flag {
	GPIO_V2_LINE_FLAG_USED			= _BITULL(0),
	GPIO_V2_LINE_FLAG_ACTIVE_LOW		= _BITULL(1),
	GPIO_V2_LINE_FLAG_INPUT			= _BITULL(2),
	GPIO_V2_LINE_FLAG_OUTPUT		= _BITULL(3),
	GPIO_V2_LINE_FLAG_EDGE_RISING		= _BITULL(4),
	GPIO_V2_LINE_FLAG_EDGE_FALLING		= _BITULL(5),
	GPIO_V2_LINE_FLAG_OPEN_DRAIN		= _BITULL(6),
	GPIO_V2_LINE_FLAG_OPEN_SOURCE		= _BITULL(7),
	GPIO_V2_LINE_FLAG_BIAS_PULL_UP		= _BITULL(8),
	GPIO_V2_LINE_FLAG_BIAS_PULL_DOWN	= _BITULL(9),
	GPIO_V2_LINE_FLAG_BIAS_DISABLED		= _BITULL(10),
	GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME	= _BITULL(11),
};
/**
 * struct gpio_v2_line_values - Values of GPIO lines
 * @bits: a bitmap containing the value of the lines, set to 1 for active
 * and 0 for inactive.
 * @mask: a bitmap identifying the lines to get or set, with each bit
 * number corresponding to the index into &struct
 * gpio_v2_line_request.offsets.
 */
struct gpio_v2_line_values {
	__aligned_u64 bits;
	__aligned_u64 mask;
};
/**
 * enum gpio_v2_line_attr_id - &struct gpio_v2_line_attribute.id values
 * identifying which field of the attribute union is in use.
 * @GPIO_V2_LINE_ATTR_ID_FLAGS: flags field is in use
 * @GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES: values field is in use
 * @GPIO_V2_LINE_ATTR_ID_DEBOUNCE: debounce_period_us field is in use
 */
enum gpio_v2_line_attr_id {
	GPIO_V2_LINE_ATTR_ID_FLAGS		= 1,
	GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES	= 2,
	GPIO_V2_LINE_ATTR_ID_DEBOUNCE		= 3,
};
/**
 * struct gpio_v2_line_attribute - a configurable attribute of a line
 * @id: attribute identifier with value from &enum gpio_v2_line_attr_id
 * @padding: reserved for future use and must be zero filled
 * @flags: if id is %GPIO_V2_LINE_ATTR_ID_FLAGS, the flags for the GPIO
 * line, with values from &enum gpio_v2_line_flag, such as
 * %GPIO_V2_LINE_FLAG_ACTIVE_LOW, %GPIO_V2_LINE_FLAG_OUTPUT etc, added
 * together.  This overrides the default flags contained in the &struct
 * gpio_v2_line_config for the associated line.
 * @values: if id is %GPIO_V2_LINE_ATTR_ID_OUTPUT_VALUES, a bitmap
 * containing the values to which the lines will be set, with each bit
 * number corresponding to the index into &struct
 * gpio_v2_line_request.offsets.
 * @debounce_period_us: if id is %GPIO_V2_LINE_ATTR_ID_DEBOUNCE, the
 * desired debounce period, in microseconds
 */
struct gpio_v2_line_attribute {
	__u32 id;
	__u32 padding;
	union {
		__aligned_u64 flags;
		__aligned_u64 values;
		__u32 debounce_period_us;
	};
};
/**
 * struct gpio_v2_line_config_attribute - a configuration attribute
 * associated with one or more of the requested lines.
 * @attr: the configurable attribute
 * @mask: a bitmap identifying the lines to which the attribute applies,
 * with each bit number corresponding to the index into &struct
 * gpio_v2_line_request.offsets.
 */
struct gpio_v2_line_config_attribute {
	struct gpio_v2_line_attribute attr;
	__aligned_u64 mask;
};
/**
 * struct gpio_v2_line_config - Configuration for GPIO lines
 * @flags: flags for the GPIO lines, with values from &enum
 * gpio_v2_line_flag, such as %GPIO_V2_LINE_FLAG_ACTIVE_LOW,
 * %GPIO_V2_LINE_FLAG_OUTPUT etc, added together.  This is the default for
 * all requested lines but may be overridden for particular lines using
 * @attrs.
 * @num_attrs: the number of attributes in @attrs
 * @padding: reserved for future use and must be zero filled
 * @attrs: the configuration attributes associated with the requested
 * lines.  Any attribute should only be associated with a particular line
 * once.  If an attribute is associated with a line multiple times then the
 * first occurrence (i.e. lowest index) has precedence.
 */
struct gpio_v2_line_config {
	__aligned_u64 flags;
	__u32 num_attrs;
	/* Pad to fill implicit padding and reserve space for future use. */
	__u32 padding[5];
	struct gpio_v2_line_config_attribute attrs[GPIO_V2_LINE_NUM_ATTRS_MAX];
};
/**
 * struct gpio_v2_line_request - Information about a request for GPIO lines
 * @offsets: an array of desired lines, specified by offset index for the
 * associated GPIO chip
 * @consumer: a desired consumer label for the selected GPIO lines such as
 * "my-bitbanged-relay"
 * @config: requested configuration for the lines.
 * @num_lines: number of lines requested in this request, i.e. the number
 * of valid fields in the %GPIO_V2_LINES_MAX sized arrays, set to 1 to
 * request a single line
 * @event_buffer_size: a suggested minimum number of line events that the
 * kernel should buffer.  This is only relevant if edge detection is
 * enabled in the configuration. Note that this is only a suggested value
 * and the kernel may allocate a larger buffer or cap the size of the
 * buffer. If this field is zero then the buffer size defaults to a minimum
 * of @num_lines * 16.
 * @padding: reserved for future use and must be zero filled
 * @fd: if successful this field will contain a valid anonymous file handle
 * after a %GPIO_GET_LINE_IOCTL operation, zero or negative value means
 * error
 */
struct gpio_v2_line_request {
	__u32 offsets[GPIO_V2_LINES_MAX];
	char consumer[GPIO_MAX_NAME_SIZE];
	struct gpio_v2_line_config config;
	__u32 num_lines;
	__u32 event_buffer_size;
	/* Pad to fill implicit padding and reserve space for future use. */
	__u32 padding[5];
	__s32 fd;
};
/**
 * struct gpio_v2_line_info - Information about a certain GPIO line
 * @name: the name of this GPIO line, such as the output pin of the line on
 * the chip, a rail or a pin header name on a board, as specified by the
 * GPIO chip, may be empty (i.e. name[0] == '')
 * @consumer: a functional name for the consumer of this GPIO line as set
 * by whatever is using it, will be empty if there is no current user but
 * may also be empty if the consumer doesn't set this up
 * @offset: the local offset on this GPIO chip, fill this in when
 * requesting the line information from the kernel
 * @num_attrs: the number of attributes in @attrs
 * @flags: flags for this GPIO line, with values from &enum
 * gpio_v2_line_flag, such as %GPIO_V2_LINE_FLAG_ACTIVE_LOW,
 * %GPIO_V2_LINE_FLAG_OUTPUT etc, added together.
 * @attrs: the configuration attributes associated with the line
 * @padding: reserved for future use
 */
struct gpio_v2_line_info {
	char name[GPIO_MAX_NAME_SIZE];
	char consumer[GPIO_MAX_NAME_SIZE];
	__u32 offset;
	__u32 num_attrs;
	__aligned_u64 flags;
	struct gpio_v2_line_attribute attrs[GPIO_V2_LINE_NUM_ATTRS_MAX];
	/* Space reserved for future use. */
	__u32 padding[4];
};
/**
 * enum gpio_v2_line_changed_type - &struct gpio_v2_line_changed.event_type
 * values
 * @GPIO_V2_LINE_CHANGED_REQUESTED: line has been requested
 * @GPIO_V2_LINE_CHANGED_RELEASED: line has been released
 * @GPIO_V2_LINE_CHANGED_CONFIG: line has been reconfigured
 */
enum gpio_v2_line_changed_type {
	GPIO_V2_LINE_CHANGED_REQUESTED	= 1,
	GPIO_V2_LINE_CHANGED_RELEASED	= 2,
	GPIO_V2_LINE_CHANGED_CONFIG	= 3,
};
/**
 * struct gpio_v2_line_info_changed - Information about a change in status
 * of a GPIO line
 * @info: updated line information
 * @timestamp_ns: estimate of time of status change occurrence, in nanoseconds
 * @event_type: the type of change with a value from &enum
 * gpio_v2_line_changed_type
 * @padding: reserved for future use
 */
struct gpio_v2_line_info_changed {
	struct gpio_v2_line_info info;
	__aligned_u64 timestamp_ns;
	__u32 event_type;
	/* Pad struct to 64-bit boundary and reserve space for future use. */
	__u32 padding[5];
};
/**
 * enum gpio_v2_line_event_id - &struct gpio_v2_line_event.id values
 * @GPIO_V2_LINE_EVENT_RISING_EDGE: event triggered by a rising edge
 * @GPIO_V2_LINE_EVENT_FALLING_EDGE: event triggered by a falling edge
 */
enum gpio_v2_line_event_id {
	GPIO_V2_LINE_EVENT_RISING_EDGE	= 1,
	GPIO_V2_LINE_EVENT_FALLING_EDGE	= 2,
};
/**
 * struct gpio_v2_line_event - The actual event being pushed to userspace
 * @timestamp_ns: best estimate of time of event occurrence, in nanoseconds.
 * @id: event identifier with value from &enum gpio_v2_line_event_id
 * @offset: the offset of the line that triggered the event
 * @seqno: the sequence number for this event in the sequence of events for
 * all the lines in this line request
 * @line_seqno: the sequence number for this event in the sequence of
 * events on this particular line
 * @padding: reserved for future use
 *
 * By default the @timestamp_ns is read from %CLOCK_MONOTONIC and is
 * intended to allow the accurate measurement of the time between events.
 * It does not provide the wall-clock time.
 *
 * If the %GPIO_V2_LINE_FLAG_EVENT_CLOCK_REALTIME flag is set then the
 * @timestamp_ns is read from %CLOCK_REALTIME.
 */
struct gpio_v2_line_event {
	__aligned_u64 timestamp_ns;
	__u32 id;
	__u32 offset;
	__u32 seqno;
	__u32 line_seqno;
	/* Space reserved for future use. */
	__u32 padding[6];
};
/*
 * ABI v1
 *
 * This version of the ABI is deprecated.
 * Use the latest version of the ABI, defined above, instead.
 */
/* Informational flags */
#define GPIOLINE_FLAG_KERNEL		(1UL